Pitch vs. trim in flight phases

On May 27, 7:42 am, wrote:
On May 16, 1:49 pm, "Ken S. Tucker" wrote:

I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is anything but
sensitive, having four or five full turns of the wheel for the trim
range. Try a Citabria sometime, where the trim is a lever that moves
about eight or ten inches for the full range. Much more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control mechanism
centered by some strong springs that supposedly simulate elevator
pressures. The anchor points for those springs are movable, and those
are what the trim mechanism moves. So in slow flight the yoke is well
back, against the springs, so that the trim moves the spring anchors
back until the pressure disappears. The yoke does not move and the
pilot, if he's "flying" right, doesn't let it move. He just trims off
the pressure. Mx's stick, on the other hand, trims electronically so
that he has to gradually center the stick to keep the nose where it's
supposed to be. Not realistic at all. And the springs in those cheap
things are so feeble as to be a joke. Flying the real airplane is much
more work. If you had realistic spring forces you'd have to bolt the
stick to the desk and anchor the chair to the floor.
I built our own procedures sim here. Proper frame welded up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete center
spring and an adjustable anchor to simulate a reaslistic trim. Real
steel throttle/prop/mixture quadrant. Robbed the electronics out of
the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for teaching
how to fly. The students use it for free to practice what they learned
on our certified Elite sim or in the air under the hood. It's much
more work to fly it, thanks to the big springs I put in it. I need to
redesign the mechanical trim to get more travel, though.
Underestimated the degree of elevator movement between high cruise and
slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken

"Ken S. Tucker" wrote in news:e7a17efd-66f3-
:

On May 27, 7:42 am, wrote:
On May 16, 1:49 pm, "Ken S. Tucker" wrote:

I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is anything
but
sensitive, having four or five full turns of the wheel for the trim
range. Try a Citabria sometime, where the trim is a lever that moves
about eight or ten inches for the full range. Much more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control mechanism
centered by some strong springs that supposedly simulate elevator
pressures. The anchor points for those springs are movable, and those
are what the trim mechanism moves. So in slow flight the yoke is well
back, against the springs, so that the trim moves the spring anchors
back until the pressure disappears. The yoke does not move and the
pilot, if he's "flying" right, doesn't let it move. He just trims off
the pressure. Mx's stick, on the other hand, trims electronically so
that he has to gradually center the stick to keep the nose where it's
supposed to be. Not realistic at all. And the springs in those cheap
things are so feeble as to be a joke. Flying the real airplane is
much
more work. If you had realistic spring forces you'd have to bolt the
stick to the desk and anchor the chair to the floor.
I built our own procedures sim here. Proper frame welded up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete center
spring and an adjustable anchor to simulate a reaslistic trim. Real
steel throttle/prop/mixture quadrant. Robbed the electronics out of
the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for teaching
how to fly. The students use it for free to practice what they
learned
on our certified Elite sim or in the air under the hood. It's much
more work to fly it, thanks to the big springs I put in it. I need to
redesign the mechanical trim to get more travel, though.
Underestimated the degree of elevator movement between high cruise
and
slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken


The dangers of using your real name.

Dan,if he comes do take pics of him and his camero.



Bertie

On May 27, 10:10 pm, "Ken S. Tucker" wrote:
On May 27, 7:42 am, wrote:



On May 16, 1:49 pm, "Ken S. Tucker" wrote:

I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is anything but
sensitive, having four or five full turns of the wheel for the trim
range. Try a Citabria sometime, where the trim is a lever that moves
about eight or ten inches for the full range. Much more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control mechanism
centered by some strong springs that supposedly simulate elevator
pressures. The anchor points for those springs are movable, and those
are what the trim mechanism moves. So in slow flight the yoke is well
back, against the springs, so that the trim moves the spring anchors
back until the pressure disappears. The yoke does not move and the
pilot, if he's "flying" right, doesn't let it move. He just trims off
the pressure. Mx's stick, on the other hand, trims electronically so
that he has to gradually center the stick to keep the nose where it's
supposed to be. Not realistic at all. And the springs in those cheap
things are so feeble as to be a joke. Flying the real airplane is much
more work. If you had realistic spring forces you'd have to bolt the
stick to the desk and anchor the chair to the floor.
I built our own procedures sim here. Proper frame welded up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete center
spring and an adjustable anchor to simulate a reaslistic trim. Real
steel throttle/prop/mixture quadrant. Robbed the electronics out of
the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for teaching
how to fly. The students use it for free to practice what they learned
on our certified Elite sim or in the air under the hood. It's much
more work to fly it, thanks to the big springs I put in it. I need to
redesign the mechanical trim to get more travel, though.
Underestimated the degree of elevator movement between high cruise and
slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken

It's for our College students only.

Dan

On May 28, 7:10 am, wrote:
On May 27, 10:10 pm, "Ken S. Tucker" wrote:



On May 27, 7:42 am, wrote:

On May 16, 1:49 pm, "Ken S. Tucker" wrote:

I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is anything but
sensitive, having four or five full turns of the wheel for the trim
range. Try a Citabria sometime, where the trim is a lever that moves
about eight or ten inches for the full range. Much more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control mechanism
centered by some strong springs that supposedly simulate elevator
pressures. The anchor points for those springs are movable, and those
are what the trim mechanism moves. So in slow flight the yoke is well
back, against the springs, so that the trim moves the spring anchors
back until the pressure disappears. The yoke does not move and the
pilot, if he's "flying" right, doesn't let it move. He just trims off
the pressure. Mx's stick, on the other hand, trims electronically so
that he has to gradually center the stick to keep the nose where it's
supposed to be. Not realistic at all. And the springs in those cheap
things are so feeble as to be a joke. Flying the real airplane is much
more work. If you had realistic spring forces you'd have to bolt the
stick to the desk and anchor the chair to the floor.
I built our own procedures sim here. Proper frame welded up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete center
spring and an adjustable anchor to simulate a reaslistic trim. Real
steel throttle/prop/mixture quadrant. Robbed the electronics out of
the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for teaching
how to fly. The students use it for free to practice what they learned
on our certified Elite sim or in the air under the hood. It's much
more work to fly it, thanks to the big springs I put in it. I need to
redesign the mechanical trim to get more travel, though.
Underestimated the degree of elevator movement between high cruise and
slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken

It's for our College students only.

No problemo, I'll enroll...which college?
Ken

wrote in news:989f5e7b-0af5-4484-9a9c-
:

On May 27, 10:10 pm, "Ken S. Tucker" wrote:
On May 27, 7:42 am, wrote:



On May 16, 1:49 pm, "Ken S. Tucker" wrote:

I was ok with the location of the trim wheel, but the adjustment
was too coarse for me, but I could be a bitchy sissy.
My wheel was graduated, with a zero mark and did not quite
give the fine adjustment I wanted. That could be cables out
to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is anything
but
sensitive, having four or five full turns of the wheel for the trim
range. Try a Citabria sometime, where the trim is a lever that
moves
about eight or ten inches for the full range. Much more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control mechanism
centered by some strong springs that supposedly simulate elevator
pressures. The anchor points for those springs are movable, and
those
are what the trim mechanism moves. So in slow flight the yoke is
well
back, against the springs, so that the trim moves the spring
anchors
back until the pressure disappears. The yoke does not move and the
pilot, if he's "flying" right, doesn't let it move. He just trims
off
the pressure. Mx's stick, on the other hand, trims electronically
so
that he has to gradually center the stick to keep the nose where
it's
supposed to be. Not realistic at all. And the springs in those
cheap
things are so feeble as to be a joke. Flying the real airplane is
much
more work. If you had realistic spring forces you'd have to bolt
the
stick to the desk and anchor the chair to the floor.
I built our own procedures sim here. Proper frame welded up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete center
spring and an adjustable anchor to simulate a reaslistic trim. Real
steel throttle/prop/mixture quadrant. Robbed the electronics out of
the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for teaching
how to fly. The students use it for free to practice what they
learned
on our certified Elite sim or in the air under the hood. It's much
more work to fly it, thanks to the big springs I put in it. I need
to
redesign the mechanical trim to get more travel, though.
Underestimated the degree of elevator movement between high cruise
and
slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken

It's for our College students only.


Whew.


Bertie

"Ken S. Tucker" wrote in
:

On May 28, 7:10 am, wrote:
On May 27, 10:10 pm, "Ken S. Tucker" wrote:



On May 27, 7:42 am, wrote:

On May 16, 1:49 pm, "Ken S. Tucker"
wrote:

I was ok with the location of the trim wheel, but the
adjustment was too coarse for me, but I could be a bitchy
sissy. My wheel was graduated, with a zero mark and did not
quite give the fine adjustment I wanted. That could be cables
out to the tail, I should have learned the mechanism!

Nothing to do with the cables. Cessna's trim is
anything but
sensitive, having four or five full turns of the wheel for the
trim range. Try a Citabria sometime, where the trim is a lever
that moves about eight or ten inches for the full range. Much
more twitchy.

As far as others have asked about sim trim, the good,
commercial training sims (Level II) have a pitch control
mechanism centered by some strong springs that supposedly
simulate elevator pressures. The anchor points for those springs
are movable, and those are what the trim mechanism moves. So in
slow flight the yoke is well back, against the springs, so that
the trim moves the spring anchors back until the pressure
disappears. The yoke does not move and the pilot, if he's
"flying" right, doesn't let it move. He just trims off the
pressure. Mx's stick, on the other hand, trims electronically so
that he has to gradually center the stick to keep the nose where
it's supposed to be. Not realistic at all. And the springs in
those cheap things are so feeble as to be a joke. Flying the real
airplane is much more work. If you had realistic spring forces
you'd have to bolt the stick to the desk and anchor the chair to
the floor.
I built our own procedures sim here. Proper frame welded
up,
proper adjustable seat, huge monitor, real rudder pedals with
realistic spring feel, real stick with a heavy non-discrete
center spring and an adjustable anchor to simulate a reaslistic
trim. Real steel throttle/prop/mixture quadrant. Robbed the
electronics out of the CH stick and pedals to drive it.
But still, it's used only as a procedures trainer, not for
teaching how to fly. The students use it for free to practice
what they learned on our certified Elite sim or in the air under
the hood. It's much more work to fly it, thanks to the big
springs I put in it. I need to redesign the mechanical trim to
get more travel, though. Underestimated the degree of elevator
movement between high cruise and slow flight.
And it has a collective for helicopter flight.

Dan

IIRC you (Dan) are in Sask, I'm just over the hills
in BC. If we're ever going by your place I'd love to
try that sim, how much do you charge?
Ken

It's for our College students only.

No problemo, I'll enroll...which college?



What if they don't have a course in sqwerl skinnin?


Bertie

On May 16, 2:55*pm, Tina wrote:
Your description of yoke pressure is vastly different from that we who
fly ga aircraft experience, which explains why you do not understand
ga trimming procedures.

We feel the pressure on the yoke reducing as trim is corrected. You
don't. We maintain the desired attitude (note - "attitude" ) with the
yoke and trim away the pressure. You can't.

The primary difference is not that he does not feel feel the reduction
in pressure on the yoke/stick as trim is applied - he does, as long as
he relaxes the pressure on the stick and allows it to move closer to
center. The primary difference is what happens if he does it wrong -
if he keeps the stick where it is as he applies trim. In your
experience, that's the correct way to trim. In his experience, it
doesn't work - the stick pressure doesn't change but the pitch does.
So far so good.

You believe that this constitutes a fundamental difference between the
sim and the real airplane. That happens not to be the case. There
are many different trim systems out there, and some of them behave not
too differently from what MX is describing.

Many of the short wing Pipers (the TriPacer being the most popular
example) used an interesting arrangement where the trim was a crank
that moved the jack screw which controlled the position of the leading
edge of the horizontal stab. The elevator hinged on the trailing edge
of the horizontal stab (which did not move - it simply turned on its
axis) and was controlled through the yoke. It was equipped with
springs that would try to center it to be in trail with the horizontal
stab. The horizontal stab only had a few degrees of travel on the
leading edge (but it was large so the trim had enough authority) so
the neutral position of the yoke changed little. It had no trim tabs
of any sort.

Trimming procedure went something like this:

Establish the desired pitch attitude with the yoke. Crank the trim
handle to change the angle of attack of the horizontal stabilizer,
which took over some of the work of the yoke. This did NOT change the
aerodynamic loads on the elevator to any appreciable extent, nor did
it really change the spring tesion much. If you tried to keep the
yoke in the same place and trim off the pressure, you would quite
possibly never get there, and you would not hold your pitch attitude.
The yoke position had to change (a lot), because the elevator position
had to change (a lot) as the horizontal stabilizer moved.

What you actually would do was relax the pressure on the yoke, letting
it move towards the point where it would fly in trail with the
horizontal stab, in order to maintain the desired pitch attitude.
THAT would relax the pressure.

Now I know that's a bit confusing, so let me step through it in
specifics. Let's say you were flying level and transitioned into the
climb. You would pull back on the yoke to deflect the elevator
upwards, to generate extra down force on the tail. This would
establish the pitch attitude you wanted. You would then crank in nose
up trim, which would lower the leading edge of the horizontal stab.
That relieved the pressure on the yoke SLIGHTLY - at least in theory.
In practice the reduction was so flight you could hardly feel it. You
would need to crank the handle a few turns just to realize you were
going the wrong way - especially if there was any turbulence.

Also, if you insisted on holding the yoke where it was, you were going
to keep pitching up. That's because the horizontal stab would start
adding downward force, without appreciably affecting the amount of
downward force the elevator was producing. As you cranked in nose up
trim (lowering the leading edge of the stab) you would also need to
relax pressure on the yoke, allowing it to move forward and lower the
trailing edge of the elevator.

If you did it wrong, you would have almost exactly the same experience
as you would with MX's sim. Doing it right was also almost the same.

Eventually, you would return the elevator to the 'in-trail' position
with the stab (a position not too terribly different from where you
started in cruise) and the plane would be in trim.

Having a joystick with centering springs and a trim wheel you must
turn as you return the joystick to center is actually a pretty fair
simulation of that system - in fact a much closer simulation than
something like a C-150/172 which has a servo tab on the elevator and a
fixed stab. On a plane like that, you do indeed hold the yoke in
position to maintain pitch attitude while moving the trim - and thus
the tab - until it reaches the proper position to keep the elevator
where you originally put it without applying pressure. A plane with a
bungee/spring trim (I believe the Piper Tomahawk had this, but it's
been so many years since I've flown one that I'm no longer certain,
though I am quite certain the Schweitzer 2-33 had it) behaves the same
way - you put the yoke where it needs to be, and then adjust tension
on the bungee/spring with the trim control until the force is trimmed
off. There is a difference. In a trim tab system, the position of
the yoke will change slightly (almost imperceptibly) during the
trimming process, because the position of the trim tab itself affect
the amount of lift the elevator (including the trim tab) exerts. In a
bungee/spring system, the elevator does not move at all. However, the
difference is not noticeable because the movement is so slight.

When I purchased a TriPacer as my first airplane, I had something like
150 hours total time, all of it in C-150/152/172 and Tomahawks.
Making the transition to the different trim system was a non-event,
except at first I kept turning the handle the wrong way half the
time. I also know someone who got his private in a Piper Colt (same
trim system as the TriPacer) and then bought a C-172. He found the
transition a total non-event. Thus I have to say that what you
consider a major difference, I see as minor at most.

Michael

Michael writes:

When I purchased a TriPacer as my first airplane, I had something like
150 hours total time, all of it in C-150/152/172 and Tomahawks.
Making the transition to the different trim system was a non-event,
except at first I kept turning the handle the wrong way half the
time. I also know someone who got his private in a Piper Colt (same
trim system as the TriPacer) and then bought a C-172. He found the
transition a total non-event. Thus I have to say that what you
consider a major difference, I see as minor at most.

I believe the objective was originally to latch onto some difference--any
difference--as "proof" that a sim was completely unlike a real aircraft. I
haven't fretted over it for exactly the reasons you describe, despite claims
here, although I do like to know how it works in specific aircraft, just as a
point of information and comparison with the sim.

Differences like trim adjustment, and even more significant changes like going
from a yoke to a stick or vice versa, are typically no big deal for a
competent pilot. The difference between an automatic transmission in a car
and a manual transmission is much greater, and yet even that requires only a
few hours of adaptation, and only in one direction.

On May 31, 3:47 am, Mxsmanic wrote:
Michael writes:
When I purchased a TriPacer as my first airplane, I had something like
150 hours total time, all of it in C-150/152/172 and Tomahawks.
Making the transition to the different trim system was a non-event,
except at first I kept turning the handle the wrong way half the
time. I also know someone who got his private in a Piper Colt (same
trim system as the TriPacer) and then bought a C-172. He found the
transition a total non-event. Thus I have to say that what you
consider a major difference, I see as minor at most.

I believe the objective was originally to latch onto some difference--any
difference--as "proof" that a sim was completely unlike a real aircraft. I
haven't fretted over it for exactly the reasons you describe, despite claims
here, although I do like to know how it works in specific aircraft, just as a
point of information and comparison with the sim.

Differences like trim adjustment, and even more significant changes like going
from a yoke to a stick or vice versa, are typically no big deal for a
competent pilot. The difference between an automatic transmission in a car
and a manual transmission is much greater, and yet even that requires only a
few hours of adaptation, and only in one direction.

The overlooked or ignored difference is if one turns the trim in the
wrong direction in a real airplane pressure on the yoke increases.
Pilots are trained to trim to reduce yoke pressure -- it is obvious
and becomes instinctive. Sims of the everyday variety do not provide
that feedback.

We trim to maintain attitude with minimal pressure on the yoke. If one
has the strength and endurance in most ga aircraft one need not trim
to maintain safe flight -- in the end it can probably be considered a
pilot comfort feature, not unlike power steering in a car.

On May 31, 10:56*am, Tina wrote:
The overlooked or ignored difference is if one turns the trim in the
wrong direction in a real airplane pressure on the yoke increases.

No, this is not universally true. I've flown airplanes where this is
not true, and clearly so has Robert Moore. These are certificated
airplanes ranging from light piston singles to transport category
multiengine jets.

Oh, if you keep doing it long enough, yes, you will eventually feel
something - but if you depend on this as your primary cue, you will
never get it right. You just need to know which way to adjust the
trim, and you need to keep moving the yoke to maintain pitch attitude.

Pilots are trained to trim to reduce yoke pressure -- it is obvious
and becomes instinctive. Sims of the everyday variety do not provide
that feedback.

And neither do some airplanes. If you are trained to depend on that
cue, you are SOL in those planes.

We do not live in a single cue world.

Michael